Because of the low particulate emissions on the vehicle side and of the low need of fuels, so-called hybrid drive mechanisms have become increasingly important in automobile construction. They contain, at least one additional electric machine as an added drive mechanism, together with a conventional internal combustion engine which is based on a piston motor with internal combustion.
It is optionally customary to operate both drive mechanisms separately and, in the case of low speeds when traveling at constant speed or at low acceleration, to exclusively use the electric machine as a drive mechanism while the internal combustion engine either runs along in idle drive or load free or is separated from the drive train and disengaged. Conversely, the internal combustion engine serves as a prime mover when driving with great need of power while the electric machine is uncoupled, runs along free of load or works as a generator.
It is further known that by simultaneous operation of both motors in the so-called boost operation, to achieve a specially high momentary driving power, the same as to use the electric machine in delay operations of the vehicle for so-called recuperation and thus recover motion energy of the vehicle in the form of electric energy.
Against these advantages of the hybrid drive mechanisms, however, stand a considerable constructional expense and often a considerable expenditure in regulation technology.
Very attractive solutions of the linkage of an internal combustion engine and an electric machine in a drive train of a vehicle result from the laid-open publications DE 199 34 696 A1 and DE 101 52 471 A1. In both cases, a planetary transmission is used as a summarizing transmission in order to couple an internal combustion engine and an electric machine, on one hand, and an input shaft of a mechanical transmission with another on the other. Planetary transmissions stand out by small construction volume and weight in relation to the transmissible outputs. By relatively simple modifications, it is optionally possible to decelerate the sun gear, the planetary gears or the ring gear and multiple possibilities of torque conversion and torque control are implemented. Such a solution, of course, associated with considerable added costs for the planetary transmission and other additional elements as clutches and brakes. Lastly, a planetary transmission requires additional installation space which considerably complicates the transmission on already existing drafts of drive mechanisms.
A simpler known version of a hybrid drive mechanism is more strongly supported on a conventional layout of a drive train and, therefore, aids better assembly and conversion of existing drive drafts. For this, a conventional drive train—consisting of an internal combustion engine, a mechanical transmission and therebetween a first clutch—is only separated in the area between the internal combustion engine and the first clutch and one electric machine is inserted, the same as a second clutch between the electric machine and the mechanical transmission.
Such a construction makes a purely electromotive start possible when the second clutch is closed and the first clutch open. The internal combustion engine can then be started while the first clutch, between an electric machine and internal combustion engine is closed. The second clutch between electric machine and transmission can be at least partly open to reduce reactions on the moving behavior of the vehicle, due to rotation uniformities, during start of the internal combustion engine.
This known solution, however, stands out by a relatively expensive regulation technology for control of both clutches according to a multiplicity of factors to be taken into account and, lastly by the need of providing a second clutch between the internal combustion engine and the transmission. This, together with the expenses associated therewith, also relative to the existing installation space, is critical in particular, since the added clutch must be capable of transmitting at least the whole power of the internal combustion engine and, due to the insertion of the second clutch, there necessarily results one other shaft to be independently supported in the area of the electric machine.
With this background, the problem on which the invention is based is to introduce a device for implementing a hybrid drive mechanism which stands out by a very small construction expenditure, a small need of installation space, low cost of parts and a simple and effective maneuverability. The invention is also based on the problem of introducing a method for control or regulation of such a device, especially for the start and stop of the internal combustion engine preferably to be carried out automatically, which stands out by simplicity and reliability.